Table 1: Chemical composition wt.% of sewage sludge ash incinerated at 800°C and silica fume determined by XRF analysis.

MaterialSiO2Al2O3Fe2O3CaOMgOSO3Na2OK2OLOI*P2O5Total

Sewage sludge ash39.0315.1317.055.801.934.040.430.622.1113.1299.26
Silica fume94.640.970.930.550.350.100.200.251.650.0499.64

L OI is the loss on ignition.